1. Field of the Invention
This invention relates to a high density slot electric connector, and especially to an electric connector for enhancing the shielding effect.
2. Description of the Prior Art
Since information technology is improved quickly, the information devices are more and more popular. Therefore, the requirement of electric connectors is increased vastly, and thus high density becomes a trend in the design of electric connector for reducing the sizes of the devices. However, in high frequency transmission, noise and interruption will become a serious problem due to the compact arrangement of the high density connectors. In general, grounding and shielding resolves these problems. In grounding, a grounding loop is used in the system with a grounding terminal connected with the grounding loop installed between the signal terminals for achieving the system grounding. In many applications of high frequency transmission, in order to insure an effective and reliable grounding, the signal terminals and grounding terminals are arranged alternatively one by one, such as in U.S. Pat. No. 5,026,292. This patent is incorporated into the present invention as a reference.
Although the aforementioned design somewhat decreases the noise and interruption, however, in a high speed and large quantity transmission system, the aforesaid design cannot effectively resolve the problem of interruption. Moreover, the number of grounding terminals is increased, so the normal clamping force that the terminals clamp the edge of the circuit track (golden finger) of a circuit substrate is also increased. As a result, the circuit substrate is difficult to pull out of and to insert into, the connector.
A slot connector for receiving a circuit substrate comprises a long insulating housing with a central slot being disposed in the longitudinal direction of the insulating housing and a bank of terminal receiving grooves being longitudinally arranged at two sides of the insulating housing. Each bank of terminal receiving grooves is formed by alternatively arranged signal terminal receiving grooves and grounding terminal receiving grooves. A plurality of signal terminals are received with the respective signal terminal receiving grooves. Each signal terminal includes a contact portion, a flexible arm, a fixing portion and a pin portion. A grounding terminal is received within the respective grounding terminal grooves. Each grounding terminal includes a contact portion, a flexible arm, a fixing portion, and a pin portion. At least one of the contact portion, elastic arm, and fixing portion of each grounding terminal has a size larger than that of the corresponding portion of the respective signal terminal.
The contact point between the grounding terminal and the circuit substrate has a position higher than the contact point between the signal terminal and the circuit substrate. When the circuit substrate has not been inserted, the gap between contact points of each paired grounding terminal to be contacted with the circuit substrate is thinner than the gap between the contact points of each paired signal terminal. Alternatively, the contact point between the signal terminal and the circuit substrate has a position higher than the contact point between the grounding terminal and the circuit substrate and when the circuit substrate has not been inserted, the gap between contact points of each paired signal terminal to be contacted with the circuit substrate is thinner than the gap between the contact points of each paired grounding terminal.